Researchers Figure Out How Cells Are Protected from Foreign DNA

Researchers at the University of Minnesota have discovered an enzyme that deactivates and degrades foreign DNA in human cells. Led by Reuben Harris, Ph.D., associate professor of biochemistry, molecular biology, and biophysics in the College of Biological Sciences, the team's findings were published online by Nature Structural and Molecular Biology on January 10.

In the study, Dr. Harris and colleagues show how APOBEC3A, an enzyme found in human immune cells, disables double-stranded foreign DNA by changing cytosines to uracils, an atypical DNA base. Persisting DNA uracils result in mutations that disable the DNA. In addition, the authors show that other enzymes step in to degrade the uracil-containing foreign DNA and remove its remains from the cell.

“Scientists have known for a long time that some human cells take up DNA better than others, but we haven't had good molecular explanations,” according to Dr. Harris. “This is definitely one of the reasons. Foreign DNA restriction is a fundamental process that could have broad implications for a variety of genetic diseases.”

Dr. Harris says that further research could enable more effective methods to swap bad genes for good ones. Dr. Harris also plans to work on why the mechanism doesn't affect a cell's own DNA.